As is well known in the aircraft industry, rapid decompression in an aircraft can have disastrous consequences. Such decompression can result from leaving a cargo door ajar, failing to lock the door properly, or if a rupture of the aircraft skin occurs for any reason. Also, during normal operations there is a need to provide a return air path within the environmental control system for conditioned air to be circulated within the aircraft cabin and cargo areas.
Accordingly, a large number of air grilles are provided in an aircraft to serve a dual purpose, i.e., delivery of fresh air, and, in an emergency, to allow for the rapid movement of very large quantities of air during decompression. Such air grilles also are desired to reduce noise in the aircraft by blocking airflow noise from coming through the grilles during normal operations. See, for example, the U.S. Pat. No. 5,137,231 by Boss, that is assigned to the assignee of this invention.
The original design requirements for this vent design include the need for a large effective opening (approximately 100 in.sup.2 for lower lobe decompression. In addition, a small effective opening (approximately 10 in.sup.2 must be provided for main cabin decompression. The vent must provide this effective opening within fractions of a second (approximately 40 msec) at a very low pressure differential (approximately 15 psig) upon the onset of a rapid decompression. The small effective opening is also required for the normal air return flow from main cabin to lower lobe. The small opening creates a pressure drop that yields a direct air return flow through the vent assembly.
Problems with most prior art air grilles are in their noise production complexity, weight, cost, cleaning, and maintenance. See also, U.S. Pat. No. 3,854,567 by Roach, U.S. Pat. No. 4,432,514 by Brandon, and U.S. Pat. No. Re. 32,554 by Murphy, each of which discloses a decompression panel having actuatable openings and spring valve means for relieving a pressure differential between an aircraft cabin and the cargo compartment.
This invention pertains to a vent assembly for use in aircraft and solves the problem of having to use heavy, mechanically complex and expensive vents for controlling return airflow and rapid decompression airflow within the fuselage of commercial aircraft. Prior attempts in solving the regulation of return airflow and rapid decompression airflow have resulted in the creation of heavy and expensive assemblies made of many diverse parts. Previous designs have relied on complex mechanical features, such as pivoting louvers hinged doors/gates, and multiple baffles, for controlling the airflow. These prior vents are very costly because of the high recurring cost associated with assembling them. These assemblies have also required extensive adjustments in order to achieve the desired airflows.